The present invention relates, in general, to transmission electron microscope specimen holders, and more particularly to a transmission electron microscope specimen holder for study of chemical reactions.
The transmission electron microscope (TEM) is widely used for materials characterization. One aspect of materials characterization is the study of the composition and lattice structures of various materials. The transmission electron microscope allows very detailed studies of the structure of materials to be performed. To this end various specimen holders are known in the prior art: a single tilting mechanism which allows the specimen to be tilted about a single axis with respect to the electron beam, a double tilt holder which tilts about two perpendicular axes, heating holders which can heat the specimen up to approximately 1,000.degree. C., and cooling holders which permit cooling of a specimen to the temperature of liquid nitrogen.
There is a need to study chemical reactions between solids and gases or between solids and liquids since these reactions are encountered in processing environments in almost any materials based industry. One such materials based industry is the semiconductor industry which depends on finely controlled chemical reactions and precisely controlled surface structures within a semiconductor wafer. Detailed study of chemical reactions involving gases or liquids is inherently difficult in an electron microscope since a high vacuum must be maintained in order for the electron beam to be adequately focused. For the lower resolution scanning electron microscope the equipment has been modified to permit a lowered vacuum in the vacuum column adjacent to the specimen. This approach is satisfactory for a scanning electron microscope due to the lower resolution and the fact that a scanning electron microscope only senses surface topography rather than internal structure.
There is a need for a specimen holder for a transmission electron microscope which will permit the study of chemical reactions involving gases and liquids interacting with the specimen. This holder should allow a relatively dense atmosphere close to the specimen and yet maintain a good enough vacuum in the microscope column so that the electron beam can be focused to obtain a high resolution. Ideally the specimen holder should be compatible with current transmission electron microscope equipment, and should allow modification of the holder or adjustment of the specimen without disassembling the entire transmission electron microscope.